Rotary electric machine

ABSTRACT

Coils in respective poles are all wound in the same shape. The coils are wound such that one of the winding ends in a predetermined layers, for a single turn, is passes to an adjacent layer, or single turns at the winding ends in a predetermined layer are wound to different adjacent positions, whereby the cross-sectional shape of the coils is unsymmetrical. The coils are wound such that part of each coil crosses or contacts an intermediate line bisecting the angle formed between the axes of the coils.

TECHNICAL FIELD

The present invention relates to a rotary electric machine such as amotor or a generator, for example, and more particularly to a rotaryelectric machine having a stator which comprises an annular array ofpoles with respective coils wound therearound.

BACKGROUND ART

Stators of rotary electric machines have a plurality of split cores.Each of the split cores comprises an arcuate yoke and a pole extendingradially inwardly from the stator, with a coil wound on the pole.

The rotary electric machines with such stators are required to maximizethe volume that the coil takes up in a slot defined between adjacentsplit cores. To meet such a requirement, it is necessary to wind moreturns of the coils around the respective split cores. There have beenproposed conventional techniques, described below, for increasing thevolume that the coil takes up in each slot.

According to the first conventional technique, coils are wound aroundadjacent cores such that the coils have different cross-sectionalshapes, filling slots defined between the cores with the coils (seeJapanese Laid-Open Patent Publication No. 2000-14066 and JapaneseLaid-Open Patent Publication No. 11-32457).

According to the second conventional technique, the width of a coil thatis first inserted into a slot defined between adjacent cores is set to ½or more of the opening width of the slot, and the coil has a slantedcross-sectional shape to avoid interference between the coil and a coilthat is subsequently inserted into the slot (see Japanese Laid-OpenPatent Publication No. 4-150749).

According to the third conventional technique, coils wound respectivelyaround adjacent cores have different cross-sectional shapes (seeJapanese Laid-Open Patent Publication No. 9-84287 and Japanese Laid-OpenPatent Publication No. 10-174331). Specifically, one of the coils has awidth that is progressively smaller toward the axis of the stator (therotational axis of the rotary electric machine), and the other coil hasan elongate rectangular cross-sectional shape and is inserted into aslot.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a rotary electricmachine having coils that take up an increased volume with respect tocores, thereby lowering the cost of a facility, reducing the number ofassembling steps, and facilitating inventory control.

According to the present invention, a rotary electric machine having astator having an annular array of poles with respective coils woundtherearound is wherein each of the coils is wound in an asymmetricalcross-sectional shape with respect to the poles in a plane perpendicularto the axis of the stator.

Using coils each having an asymmetrical cross-sectional shape, a rotaryelectric machine having a stator having coils taking up an increasedvolume can be constructed of a single type of poles.

The coils may have portions extending beyond or held in contact with amedium line or an intermediate line which divides the angle formedbetween the axes of adjacent coils into two equal angles, in the planeperpendicular to the axis of the stator. Alternatively, one of adjacentones of the coils may have a portion extending beyond or held in contactwith a tangential line interconnecting ends of adjacent layers of theother one of the adjacent ones of the coils, in the plane perpendicularto the axis of the stator. With this arrangement, the volume that thecoils take up may further be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view, with a sealant partly omitted from illustration,of the stator of a rotary electric machine according to an embodiment ofthe present invention;

FIG. 2 is a perspective view of a split core to be assembled in thestator;

FIG. 3 is a perspective view, partly cut away, of a terminal and aninsulator on which the terminal is assembled;

FIG. 4 is a perspective view of insulators, terminals, and a laminatedsteel plate assembly;

FIG. 5 is a perspective view of the insulator and the terminal as viewedfrom a radially outward direction;

FIG. 6 is a plan view showing the manner in which a split core is fixedto a jig before a coil is wound around the split core;

FIG. 7 is a plan view showing a state immediately before a coil is woundaround a split core;

FIG. 8 is a plan view showing a process of cutting a blank wire afterthe coil is wound around the split core;

FIG. 9 is a plan view, partly omitted from illustration, showing aprocess of winding a first layer of turns around the split core;

FIG. 10 is a plan view, partly omitted from illustration, showing aprocess of winding a second layer of turns around the split core;

FIG. 11 is a plan view, partly omitted from illustration, showing aprocess of winding a turn from the second layer to a third layer aroundthe split core;

FIG. 12 is a plan view, partly omitted from illustration, showing aprocess of winding a second turn of the third layer around the splitcore;

FIG. 13 is a plan view, partly omitted from illustration, showing aprocess of winding a third turn of the third layer around the splitcore;

FIG. 14 is a plan view, partly omitted from illustration, showing aprocess of winding the third layer of turns around the split core;

FIG. 15 is a plan view, partly omitted from illustration, showing aprocess of winding a fourth layer of turns around the split core;

FIG. 16 is a plan view, partly omitted from illustration, showing aprocess of winding a first turn of a fifth layer around the split core;

FIG. 17 is a plan view, partly omitted from illustration, showing aprocess of winding the fifth layer of turns around the split core;

FIG. 18 is a cross-sectional view of the coil in a plane perpendicularto the axis of the stator;

FIG. 19 is an enlarged fragmentary plan view showing the relativepositional relationship between adjacent coils with respect to a centralline;

FIG. 20 is an enlarged fragmentary plan view showing the relativepositional relationship between adjacent coils with respect to a linetangential to coils;

FIG. 21 is a fragmentary plan view of the stator with a split core setin a housing;

FIG. 22 is a fragmentary plan view of the stator with two split coresset in the housing; and

FIG. 23 is a fragmentary plan view of the stator with eighteen splitcores set in the housing.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, a stator 10 according an embodiment of the presentinvention comprises a stator with coils connected in a so-calledthree-phase Y connection, and has input terminals U, V, W of the Yconnection and eighteen split cores 12.

As shown in FIGS. 2 through 5, each of the split cores 12 beforeassembled into the stator 10 comprises a laminated steel plate assembly24 made of a stack of steel plates that are stamped out to asubstantially T-shape by a press, insulators 21, 22 insulating thelaminated steel plate assembly 24 from the exterior, a coil 14 woundaround the laminated steel plate assembly 24 with the insulators 21, 22interposed therebetween, and terminals 18, 28 made of metal.

As described above, the laminated steel plate assembly 24 has asubstantially T-shape and has a portion 24 a corresponding to the upperside of the “T” shape and serving as a yoke of the stator. The laminatedsteel plate assembly 24 also has a portion 24 b corresponding to a lowerextension of the “T” shape and serving as a pole (or a salient pole) ofthe stator 10.

The coil 14 comprises a wire 13 having an insulating film. The coils 14disposed on a radially inner side of the stator 10 (in the directionindicated by the arrow A) have ends serving as extensions 16 that areelectrically connected to each other by the terminals 18 of the splitcores 12. Therefore, the terminals 18 form a neutral point of the Yconnection. The other ends of the coils 14 which are disposed on aradially outer side of the stator 10 (in the direction opposite to thedirection indicated by the arrow A) are connected to either one of theinput terminals U, V, W through an annular input line bus bar (notshown). Specifically, the other ends of the coils 14, which are woundaround six split cores 12 that are disposed as every three split cores,are connected to the input terminal U. The other ends of the coils 14which are wound around six split cores 12 that are disposed as everythree split cores, different from the above six split cores 12, areconnected to the input terminal V. Furthermore, the other ends of thecoils 14, which are wound around the remaining six split cores 12, areconnected to the input terminal W. The split cores 12, the inputterminals U, V, W, and the input line bus bar are assembled on a hollowhousing (or case) 19 (see FIG. 1).

The terminals 18 are located in an annular groove 88 to be describedlater and insulated by a sealant 20 filled in the annular groove 88.

As described above, the split cores 12 are constructed of the terminals18 of metal fixing the extensions 16 as ends of the coils 14 disposed onthe radially inner side of the stator 10 and electrically connected tothe coils 14, and the terminals 28 of metal fixing the other ends of thecoils 14 disposed on the radially outer side of the stator 10 andelectrically connected to the coils 14. The terminals 18 and theterminals 28 are made of the same material.

Each of the extensions 16 has a first extension 16 a extending in theradially inward direction of the stator 10, a second extension 16 bextending from the first extension 16 a in a circumferential directionof the stator 10, and a third extension 16 c extending from the secondextension 16 b in the radially outward direction of the stator 10.Therefore, the extension 16 is of a curved and bent structure. Theterminal 18 has a first fixing portion 18 b on one end thereof, tworecesses 30, 32 are formed in front of and behind the first fixingportion 18 b (in the direction indicated by the arrow A). The firstextension 16 a has a base portion positionally fixed by the first fixingportion 18 b and electrically connected to the first fixing portion 18b, and guided by the two recesses 30, 32 in the direction indicated bythe arrow A.

The second extension 16 b is curved or bent perpendicularly to the firstextension 16 a, and the third extension 16 c extends perpendicularly tothe second extension 16 b. Actually, the first extension 16 a, thesecond extension 16 b, and the third extension 16 c are disposed in thesame hypothetical plane.

As shown in FIGS. 3 through 5, the terminal 18 (and 28) comprises asubstantially T-shaped metal terminal and has an insert 18 a (28 a) tobe inserted into a slot 70 (84) in the insulator 21, the first fixingportion 18 b (28 b) disposed on one end of the terminal 18 for fixingthe first extension 16 a, and a second fixing portion 18 c (28 c)disposed on the other end of the terminal 18 for fixing the thirdextension 16 c of another adjacent split core 12. The terminal 18 (28)also has a small boss (engaging portion) 18 d (28 d) formed by a presssuch as a punch or the like.

As shown in FIG. 4, the insulator 21 has a coil winding portion 34 forwinding the coil 14 therearound, a peripheral wall 40 disposed on theradially inner side of the stator 10 perpendicularly to the plane of thecoil winding portion 34, and a peripheral wall 44 disposed on theradially outer side of the stator 10 perpendicularly to the plane of thecoil winding portion 34. The insulator 22 has a coil winding portion 36for winding the coil 14 therearound, a peripheral wall 42 disposed onthe radially inner side of the stator 10 perpendicularly to the plane ofthe coil winding portion 36, and a peripheral wall 46 disposed on theradially outer side of the stator 10 perpendicularly to the plane of thecoil winding portion 36. When the insulator 22 is inserted upwardly intothe insulator 21, a portion of the coil winding portion 34 and a portionof the coil winding portion 36 overlaps and are coupled to each other, aportion of the peripheral wall 40 and a portion of the peripheral wall42 overlaps and are coupled to each other, and a portion of theperipheral wall 44 and a portion of the peripheral wall 46 overlaps andare coupled to each other. The insulators 21, 22 are thus integrallycombined with each other, forming a hole 48 within the integrallycombined insulators 21, 22. The laminated steel plate assembly 24, whichis made of a stack of steel plates, is inserted into the hole 48,thereby electrically insulating the laminated steel plate assembly 24from the coil 14.

The insulator 21 has, on a radially inner upper section (opposite to theinsulator 22 disposed in a lower section), a first upward wall 50serving as part of the peripheral wall 40 and extending vertically alongthe axis of the stator 10 (the rotational axis of the rotary electricmachine), a second upward wall 52 spaced from the first upward wall 50in the radially inward direction of the stator 10 and extendingsubstantially parallel to the first upward wall 50, and a joint surface54 interconnecting the lower end of the first upward wall 50 and thelower end of the second upward wall 52.

The insulator 21 has two bases 56, 58 extending in the radially inwarddirection of the stator 10 from respective left and right portions ofthe lower end of the second upward wall 52. On the right-hand(hereinafter simply referred to as “right”, and an opposite left-handside of right as “left”) base 58 in FIG. 4, a portion of the secondupward wall 52 is thicker than the other portion of the second upwardwall 52, providing a side of the recess 30. The thicker portion servesas a guide portion 60 for guiding the extension 16 of the coil 14 in thedirection in which it extends (in the direction indicated by the arrowA).

The second upward wall 52 has a recess 64 defined in a left portionthereof and positioned in symmetrical relation to the recess 30. Therecess 32 is defined in the first upward wall 50 which is presentradially outwardly (in the direction opposite to the direction indicatedby the arrow A) of the second upward wall 52 having the recess 30 withrespect to the stator 10.

A tooth 68 having a recess (engaged portion) 66 defined in thecircumferential direction of the stator 10 is disposed vertically on thefirst upward wall 50 on the radially inner side of the stator 10. A slot70 is defined between the tooth 68 and the first upward wall 50.

A protrusion 72 projects to the right from the guide portion 60, thejoint surface 54, and the first upward wall 50.

FIG. 5 shows the insulator 21 illustrated in FIG. 4, as viewed fromobliquely above its rear side. As shown in FIG. 5, the peripheral wall44 has a recess 74 defined therein at a position leftward of the centerthereof (rightward in FIG. 5) for passing the other end of the coil 14therethrough. The peripheral wall 44 also has a flaring portion 75disposed on a left end thereof (right end in FIG. 5) and projecting inthe radially outward direction of the stator 10, providing a dent 76defined in the left end of the peripheral wall 44 in the radially inwarddirection of the stator 10. The peripheral wall 44 has a protrusion 78disposed on a right end thereof (left end in FIG. 5) and projecting tothe right of the peripheral wall 44. The protrusion 78 fits in the dent76 of an adjacent split core 12.

A tooth 80, which is of substantially the same shape as the tooth 68, isdisposed vertically radially outwardly (in the direction opposite to thedirection indicated by the arrow A) of the peripheral wall 44 in acentral region along the circumferential direction of the stator 10. Thetooth 80 has a recess 82 defined therein which extends in thecircumferential direction of the stator 10. A slot 84, which is ofsubstantially the same shape as the slot 70, is defined between thetooth 80 and the peripheral wall 44.

The joint surface 54, the first upward wall 50, and the second upwardwall 52 have left ends whose inner surfaces are convex, providing a dent86. The dent 86 is shaped to fit over the protrusion 72.

If the insulators 21, 22 are made of PPS (polyphenylene sulfide), thenthey provide excellent heat resistance, mechanical strength, rigidity,electric insulation, dimensional stability, and creep resistance.

A process of assembling the split core 12 of the insulators 21, 22, theterminals 18, 28, the laminated steel plate assembly 24, and the coil 14will be described below.

First, the insert 18 a of the terminal 18 is inserted into the slot 70(see FIG. 3) in the insulator 21. Since the small boss 18 d of theterminal 18 engages in the recess 66 in the tooth 68, the insulator 21is prevented from being dislodged from the terminal 18. Similarly, theinsert 28 a of the terminal 28 is inserted into the slot 84 (see FIG. 3)in the insulator 21. The small boss 28 d engages in the recess 82,preventing the insulator 21 from being dislodged from the terminal 28.

Then, the laminated steel plate assembly 24, which is made up of a stackof steel plates, is inserted into the hole 48 (see FIG. 4) that isdefined by the insulators 21, 22.

Then, the blank wire 13 is wound around the coil winding portions 34,36, forming the coil 14. Specifically, as shown in FIG. 6, with thelaminated steel plate assembly 24 inserted in the hole 48, theinsulators 21, 22 are fixed in position by a first jig 100 and a secondjig 102. The first jig 100 holds the radially outer side of theinsulator 21, i.e., the peripheral wall 44 thereof. The first jig 100can be rotated about an axis C by a winding motor (not shown). Thesecond jig 102 holds the radially inner side of the insulator 21, i.e.,the peripheral wall 40 thereof.

As shown in FIG. 7, the blank wire 13 is twined successively around pins102 a through 102 d mounted on the upper surface of the second jig 102by a blank wire guide mechanism (not shown). The end of the blank wire13 that extends ahead of the pin 102 a is fixed integrally to the secondjig 102 by a chuck (not shown). The blank wire guide mechanism guidesthe blank wire 13 along the side of the guide portion 60, and alsoguides the blank wire 13 through the recess 30, the fist fixing portion18 b, and the recess 32 toward the coil winding portions 34, 36. At thistime, the relative positions and shapes of the pins 102 c, 102 d and theguide portion 60 form the first extension 16 a, the second extension 16b, and the third extension 16 c.

The end of the blank wire 13 that is guided to the coil winding portions34, 36 extends from a blank wire supply 104. The blank wire supply 104is movable back and forth in the directions indicated by the arrow Bparallel to the axis C. The distance that the blank wire supply 104 ismovable back and forth can be controlled in synchronism with the angulardisplacement of the winding motor.

The winding motor then rotates the first and second jigs 100, 102 andthe insulators 21, 22 about the axis C. At this time, the blank wiresupply 104 is moved back and forth in the directions indicated by thearrow B depending on the angular displacement of the winding motor,winding the blank wire 13 around the coil winding portions 34, 36.

Then, as shown in FIG. 8, after the blank wire 13 is wound into the coil14, the blank wire guide mechanism guides the blank wire 13 through therecess 74 and the first fixing portion 28 b and around pins 100 a, 100b. The blank wire 13 is guided to pass through a groove definedcentrally in the pin 100 b.

Then, the opposite ends of the blank wire 13 which extend from the coil14 are temporarily fixed by the first fixing portion 18 b of theterminal 18 and the second fixing portion 28 b of the terminal 28.

The opposite ends of the blank wire 13 which extend from the coil 14 arecut off at cut-off regions 106, 108. The cut-off region 106 is locatedbetween the pins 102 c, 102 d. The location where the third extension 16c is positioned at the second fixing portion 18 c of an adjacent splitcore 12 when the split core 12 is assembled on the stator 10 ispreferable for use as the cut-off region 106 a. The cut-off region 108is located radially outwardly of the first fixing portion 28 b.

Thereafter, the split core 12 is removed from the first jig 100 and thesecond jig 102. The process of winding the coil 14 is now finished.

Then, a process of winding the blank wire 13 into the coil 14 around thecoil winding portions 34, 36 will be described in greater detail withreference to FIGS. 9 through 15. In FIGS. 9 through 15, the first jig100, the second jig 102, and the blank wire supply 104 are omitted fromillustration for an easier understanding. In FIGS. 9 through 15, thedirection indicated by the arrow A is referred to as a downwarddirection, and the direction opposite thereto as an upward direction. Inthe description which follows, a first turn of a first layer of the coil14 is referred to as a turn A1, and second and following turns thereofas a turn A2, a turn A3, . . . . A first turn of a second layer of thecoil 14 is referred to as a turn B1, and second and following turnsthereof as a turn B2, a turn B3, . . . . Similarly, turns of a thirdlayer are referred to as turns Cn (n=1, 2, 3, . . . ), turns of a fourthlayer as turns Dn, and turns of a fifth layer as turns En.

As shown in FIG. 9, turns A1 through A15 of the first layer are woundsuccessively upwardly in an array. The fifteen turns of the first layerthus wound cover the coil winding portions 34, 36 (see FIG. 4) with theblank wire 13 substantially free of gaps.

Then, the blank wire 13 is guided from a grove 200 defined on the leftbetween the turn A15 and the peripheral wall 44 to an aligning groove202 that is defined on the right by the turn A15 and the turn A14 of thefirst layer, starting to wind the turn B1 of the second layer. The turnB1 can stably be wound as it is wound along the aligning groove 202.

Thereafter, as shown in FIG. 10, the turns B1 through B13 (final turn ofthe second layer) of the second layer are wound successively downwardlyin an array.

Then, the blank wire 13 is guided from a grove 204 positioned on theleft directly below the turn B13 to an aligning groove 206 that isdefined on the right by the turn B12 and the turn B13 of the secondlayer, starting to wind the turn C1 of the third layer. At this time,the turn C1 is guided across the turn B13. The turn C1 can stably bewound as it is positioned in the aligning groove 206.

Then, as shown in FIG. 11, the blank wire 13 is guided from a groove 208positioned on the left directly below the turn C1 to a groove 210 thatis defined on the right by an introduced end 207 of the turn A1 which isintroduced from the recess 32 and the turn B13 of the second layer, thuswinding the turn C2.

Then, as shown in FIG. 12, the blank wire 13 is guided from an aligninggroove 212 which is defined on the left by the turn B13 and the turn C1to a groove 214 which is defined on the right by the turns C1, C2 of thethird layer, thus winding the turn C3.

Then, as shown in FIG. 13, the blank wire 13 is guided from a groove 216which is positioned on the left immediately above the turn C3 to agroove 218 which is positioned on the right immediately above the turnC1, thus winding the turn C4.

Thereafter, the turns of the third layer following the turn C4 are woundsuccessively in an array based on the turn C1, until the turn C15 iswound in abutment against the peripheral wall 44 (see FIG. 14).

Then, the blank wire 13 is guided from an aligning groove 220 which isdefined on the left by the turn C14 and the turn C15 to an aligninggroove 222 on the right, starting to wind the turn D1 of the fourthlayer. As shown in FIG. 15, the turns of the fourth layer are woundbased on the turn D1, until the seventh turn D7 is wound.

Then, the blank wire 13 is guided from a groove 224 which is positionedon the left immediately below the turn D7 to an aligning groove 226which is defined on the right by the turn D5 and the turn D6, startingto wind the turn E1 of the fifth layer.

Then, as shown in FIG. 16, the blank wire 13 is guided from an aligninggroove 228 which is defined on the left by the turn D3 and the turn D4to an aligning groove 230 which is defined on the right by the turn D2and the turn D3, thus winding the turn E2. Thereafter, as shown in FIG.17, the turns of the fifth layer following the turn E2 are woundsuccessively in an array based on the turn E2, until the turn E4 iswound in abutment against the peripheral wall 44. Subsequently, theblank wire 13 is threaded through the recess 74, and the winding of thecoil 14 is finished.

According to the present embodiment, as shown in FIG. 18, the wound coil14 has a cross-sectional shape which is asymmetrical with respect to theaxis C. Specifically, the first layer has fifteen turns on each of itsleft and right sides and the second layer has fourteen turns on each ofits left and right sides, and hence these layers are symmetrical inshape. However, the third layer has fourteen turns on the right side andthirteen turns on the left side, and hence is asymmetrical in shape (seehatched turns 302, 306). Similarly, the fourth layer has seven turns onthe right side and eight turns on the left side, and hence isasymmetrical in shape. Accordingly, the third and fourth layers may becounted as having 13.5 turns and 7.5 turns, respectively.

The fifth layer has four turns on each of the left and right sides, butis asymmetrical in shape because hatched turns 300, 304 are turned indifferent positions on the left and right sides.

Therefore, the coil 14 has an asymmetrical shape with respect to theaxis C because of the two different structures, i.e., a structure inwhich one of the left and right turns of a certain layer is shifted toan adjacent layer, providing a 0.5 turn per layer, and a structure inwhich the positions of corresponding left and right turns of one layerare shifted.

In FIG. 18, the structure in which one of the left and right turns of acertain layer is shifted to an adjacent layer is conceptually indicatedby the arrow D, and the means by which the positions of correspondingleft and right turns of one layer are shifted is conceptually indicatedby the arrow E.

The relative positional relationship between adjacent split cores 12 atthe time coils 14 thus wound are assembled on the stator 10 will bedescribed below with reference to FIGS. 19 and 20. In FIGS. 19 and 20, aregion of the split cores 12 is provided for illustrative purposes, andthe relative positional relationship will be described based on theregion.

As shown in FIG. 19, a medium line or an intermediate line M forproviding a region of the split cores 12 is provided for illustrativepurposes. The medium line M is provided at a position which divides theangle between the axes C (see FIG. 1) of the respective split cores 12into two equal angles at the center C (see FIG. 1) of the stator 10.

As can be seen from FIG. 19, the left coil 14 has hatched turn portions310, 312 extending beyond the medium line M, and the right coil 14 hashatched turn portions 314, 316 extending beyond the medium line M.

The method by which the coil 14 is wound is not limited to the one shownin FIG. 19. However, the hatched turn portion 310 may be wound in analigning groove defined by the turn D4 and the turn D5, as indicated bythe two-dot-and-dash line 310 a.

The hatched turn portions 310, 312, 314, 316 shown in FIG. 19 are partof the hatched turns 300, 302, 304, 306, respectively, shown in FIG. 18.It can be understood that the asymmetrical portions of the coil 14effectively fill dead spaces.

Then, as shown in FIG. 20, tangential lines interconnecting ends ofadjacent layers, e.g., a tangential line 320 interconnecting the leftends of the turn E2 and the turn E1, and a tangential line 322interconnecting the left ends of the turn D7 and the turn C3, areprovided. Furthermore, a tangential line interconnecting ends ofadjacent turns of the same layer, i.e., a tangential line 324interconnecting the turn E1 and the turn E2 of the fifth layer, providesa region of the split cores 12. With the region of the split cores 12being thus relatively small, a hatched turn portion 326 of the left coil14 extends beyond the tangential line 320, and a hatched turn portion328 of the right coil 14 extends beyond the tangential line 324 and hasits vertex 330 held in contact with the tangential line 322.

In this manner, the coils 14 of the respective split cores 12 haveportions entering into empty areas of the adjacent split cores 12.Therefore, dead spaces are effectively utilized to increase the volumesthat the coils take up. As can be seen from FIGS. 19 and 20, theadjacent coils 14 do not interfere with each other.

A procedure for assembling split cores 12 with coils 14 woundtherearound onto the stator 10 will be described below with reference toFIGS. 21 through 23.

First, as shown in FIG. 21, a first split core 12 (distinguished as asplit core 12 a) is positioned and set in the housing 19.

Then, as shown in FIG. 22, a second split core 12 (distinguished as asplit core 12 b) is set on the right side of the split core 12 a, i.e.,counterclockwise in FIG. 22. At this time, if the split core 12 b is setfrom above in the housing 19, the third extension 16 c of the coil 14 ofthe split core 12 b is positioned on the second fixing portion 18 c ofthe terminal 18 of the split core 12 a. The third extension 16 c of thecoil 14 is thus brought into engagement with the second fixing portion18 c by such a simple insertion process.

At this time, since the dent 86 (see also FIG. 5) of the insulator 21 ofthe split core 12 a fits over the protrusion 72 of the insulator 21 ofthe split core 12 b, the joint surfaces 54, the first upward walls 50,and the second upward walls 52 are held in abutment against each otherin partly overlapping relation, providing step-free surfaces across thejoint. Thus, in the area where the split cores 12 a, 12 b are joinedtogether, the first upward walls 50 and the second upward walls 52 ofthe insulators 21 are joined together without any gaps, forming anannular groove 88.

The process of bringing the third extension 16 c into engagement withthe second fixing portion 18 c and the process of joining the adjacentsplit core 12 b do not need to be carried out simultaneously. After thethird extension 16 c is brought into engagement with the second fixingportion 18 c, the split core 12 b may be joined.

Thereafter, another split core 12 is joined to the left side of thesplit core 12 b according to the same procedure as descried above, andthen other split cores are successively joined until a seventeenth splitcore 12 (distinguished as a split core 12 q, see FIG. 23) is joined.

Then, as shown in FIG. 23, a final split core 12 (distinguished as asplit core 12 r) is set between the split core 12 q and the split core12 a. At this time, the extension 16 of the coil 14 of the split core 12a is retracted out of interference with the split core 12 r.

After the split core 12 r is set, the extension 16 of the coil 14 of thesplit core 12 a is returned to its original position and brought intoengagement with the second fixing portion 18 c of the split core 12 r.

The split cores 12 do not need to be directly mounted in the housing 19,but may be mounted on a holder or a ring and thereafter pressed into thehousing 19.

When the eighteen split cores 12 are joined together, the annular groove88 is completed.

Then, the first extensions 16 a of the coils 14 and the first fixingportions 18 b of the terminals 18 are connected. The third extensions 16c of the coils 14 and the second fixing portions 18 c of the terminals18 are connected. Specifically, the first fixing portion 18 b is pressedwith heat against the first extension 16 a, melting away the insulationcover on the first extension 16 a and electrically connecting the copperwire of the first extension 16 a to the first fixing portion 18 b. Thethird extension 16 c and the second fixing portion 18 c are similarlyconnected to each other by thermal compression. The second fixingportions 28 c of the terminals 28 on the radially outer sides of thesplit cores 12 are also connected to the input line bus bar in the samemanner as described above.

The coils 14 thus have common lines connected to each other through theterminals 18. Since the terminals 18 are part of the split cores 12, noseparate connecting parts are necessary to connect the coils 14. Asdedicated separate parts such as common line bus bars or printed circuitboards are not required, the connecting procedure can easily beperformed, and the coils 14 can be connected with reduced man-hours.

With the rotary electric machine according to the present embodiment, asdescribed above, the volume that the coils 14 take up can be increasedby using only one type of coils 14. If the blank wire 13 has a largediameter, in particular, then the steps between adjacent layers of thecoils 14 and the gaps between adjacent turns are large. However, deadspaces produced by thus steps and gaps can effectively be filled.

Inasmuch as the split cores 12 are of one type, the winding apparatusand the winding process may also be of one type. Therefore, the cost ofthe facility and the number of manufacturing steps can be reduced,making it easier to perform manufacturing control and inventory control.

The basic structure of the split cores 12 is applicable regardless ofthe number of poles of rotary electric machines. For example, it isapplicable to rotary electric machines having an odd number of poles.

The stator 10 may not necessarily be of a split structure, but may havean integral core (or stator) having a plurality of radially projectingpoles, around which the coils 14 may directly be wound.

The rotary electric machine according to the present invention is notlimited to the above embodiment, but may employ various structureswithout departing from the scope of the invention.

INDUSTRIAL APPLICABILITY

As described above, the rotary electric machine according to the presentinvention has coils that take up an increased volume with respect tocores, thereby lowering the cost of a facility, reducing the number ofassembling steps, and facilitating inventory control.

1. A rotary electric machine having a stator having an annular array ofpoles with respective coils wound therearound, wherein each of saidcoils is wound in an asymmetrical cross-sectional shape with respect tosaid poles in a plane perpendicular to the axis of said stator.
 2. Arotary electric machine according to claim 1, wherein said coils haveportions extending beyond or held in contact with a medium line whichdivides the angle formed between the axes of adjacent ones of said coilsinto two equal angles, in the plane perpendicular to the axis of saidstator.
 3. A rotary electric machine according to claim 1, wherein oneof adjacent ones of said coils has a portion extending beyond or held incontact with a tangential line interconnecting ends of adjacent layersof the other one of said adjacent ones of said coils, in the planeperpendicular to the axis of said stator.
 4. A rotary electric machineaccording to claim 1, wherein one of adjacent ones of said coils has aportion extending beyond or held in contact with a tangential lineinterconnecting ends of adjacent turns of the same layer of the otherone of said adjacent ones of said coils, in the plane perpendicular tothe axis of said stator.
 5. A rotary electric machine according to claim1, wherein said asymmetrical cross-sectional shape of each of said coilsis formed by shifting at least one of turns of said each coil to anadjacent layer thereof.
 6. A rotary electric machine according to claim1, wherein said asymmetrical cross-sectional shape of each of said coilsis formed by making the positions of turns of said each coilasymmetrical.
 7. A rotary electric machine according to claim 5, whereinsaid asymmetrical cross-sectional shape of each of said coils is formedby winding said turns successively along aligning grooves definedbetween said turns.
 8. A rotary electric machine according to claim 5,wherein when each of said coils having a plurality of layers eachcomprising said turns is formed, said turns are wound across saidlayers.
 9. A rotary electric machine according to claim 6, wherein saidasymmetrical cross-sectional shape of each of said coils is formed bywinding said turns successively along aligning grooves defined betweensaid turns.
 10. A rotary electric machine according to claim 6, whereinwhen each of said coils having a plurality of layers each comprisingsaid turns is formed, said turns are wound across said layers.